The present invention relates to a motor vehicle performance test apparatus, and more particularly to a motor vehicle performance test apparatus for conducting various tests of various motor vehicles including a four-wheel drive vehicle.
Among auto repair shops, it is very popular to use a chassis dynamometer when conducting running test of a motor vehicle. Most chassis dynamometers, however, are not suitable for testing a four-wheel drive vehicle, since they are so constructed as to measure driving torque of rear or front driving wheels of a two-wheel drive vehicle. Thus, there is a growing need among auto repair shop owners for an inexpensive and compact apparatus for conducting running test of a four-wheel drive vehicle.
JP No. 60-253838 A discloses a motor vehicle running test apparatus for a four-wheel drive vehicle. This known apparatus comprises a front wheel roller adapted to contact with front wheels of a four-wheel drive vehicle, a rear wheel roller adapted to contact with rear wheels thereof, and two direct-current (dc) dynamometers for controlling loads applied to the front and rear rollers, respectively. According to this known apparatus, a revolution speed of the dynamometer for the front wheel roller is detected by a revolution speed detector and fed to a vehicle speed detector where a vehicle speed is determined. The first derivative of the vehicle speed with respect to time is calculated to determine a vehicle acceleration. Based on the acceleration, a ratio of load applied to the front wheel roller to load applied to the rear wheel roller is set using an empirically determined data map. The dynamometers are so controlled as to apply loads on the front and rear wheel rollers at the ratio which has been set.
This known apparatus, however, suffers from problems that it is difficult to allow both of the front and rear wheel rollers to rotate at the same speed and expensive direct-current dynamometers are required to compensate for a difference between inertia of each roller and inertia of the vehicle under test. This has caused an increase in cost of the apparatus.
JP No. 61-65133 A discloses a motor vehicle running test apparatus designed to continuously vary a force with which each of front and rear wheel rollers contacts firmly with driving wheels by lifting the rollers. In order to allow lifting movement of the rollers, this known apparatus uses flexible joints via which the front and rear wheel rollers are connected to gear boxes, respectively. These gear boxes are connected in series via a spline shaft to a direct-current (dc) dynamometer.
In this known apparatus, there is established between the front and rear wheel rollers a power delivery system by the gear boxes and the spline shaft. The components of the power delivery system demands substantial strength to withstand power to be delivered, making the power delivery system bulky and heavy. Substantial inertia and mechanical loss have to be take into account and besides the direct-current dynamometer is used. This has caused an increase in cost of the apparatus.
An object of the present invention is to provide a less expensive and less bulky motor vehicle performance test apparatus which is constructed and arranged, without a direct-current dynamometer that is expensive and a bulky and heavy power delivery system, as to be capable of conducting various tests of a four-wheel drive vehicle.